THE MOXTHLY BULLETIN". 



379 



Mechanical Control. 



It was with a view to capturino- the lioppers in the early spring before 

 any eggs wonld be deposited or before any injury was done, that a screen 

 box was devised. This consisted of a square framework covered with 

 wire netting, open on one side and with a galvanized iron tray forming 

 the bottom, with a V-shaped qpening, which allowed it to be pushed 

 onto the vine, at the same time the hoppers being jarred off and caught 

 in the crude oil that was smeared on the screen. This was intended 

 for vines headed some little distance from the ground, for most of the 

 hoppers fell on the tray or low down on the sides. This sort of an 

 apparatus is not satisfactory for vines that are so low headed as many 

 of them are in this vicinity, nor is it applicable for trellised vines. 

 "With the right shaped vines such a cage can be used very successfully 

 and 90 per cent of the hoppers captured at a time when for each one 

 taken it n^eans, as I have shown, possibly 5,000 less later in the season. 



It was thought that a cheap apparatus as I have described, that any- 

 body could make, would appeal to practical growers, but that is not the 

 case. California growers have an inherent desire to do things on a 

 large scale, and anything that can be pulled with four or five, or a couple 

 of dozen horses, or a caterpillar engine, comes nearer to satisfying their 

 idea of how things should be done. For this reason I have some hopes 

 that such a machine as Mr. Driver of Dinuba has devised may be made 

 to work successfully. The idea of drawing the hoppers away from the 

 vine by suction is an old one and has not yet been thoroughly tested out. 

 I do not believe, however, that midsummer or later is the time to operate 

 such a machine. Great numbers of hoppers are, of course, captured at 

 this time, and it is spectacular enough, but they should be captured 

 before they become so abundant, and before the vines show such con- 

 spicuous injury as they do at this season. By this time practically all 

 the injury has been done and all the young have developed, and there is 

 no assurance that they may not be abundant there the following year. 



If such a machine would take the over-wintering hoppers at a time 

 when the shoots are six to eight inches long, before any damage was 

 clone and before breeding commenced, it would be the solution of the 

 hopper question. I hope those interested in such a machine will try it 

 early next spring. Some preliminary experiments in spraying into a 

 canvas canopy pulled over the vines also gave some promise of control 

 at this season. 



Conclusion. 

 Those of you who came to hear definite and specific recommendations 

 for the successful control of the grape-leaf hopper I fear will be disap- 

 pointed. I do not believe in giving such recommendations until we have 

 them and they are thoroughly tested out in practical work. Your 

 experiment station started an investigation of this insect five or six 

 years ago to continue at least two years. During the first year it was 

 intended to study the insect itself, since this is essential for any control 

 work, and the second vear to test various methods of control. A portion 



